Telephone-transmitter



HAMMOND V. HAYES, OF CAMBRIDGE, MASSACHUSETTS.V

SPECIFICATION' forming part of Letters Patent N o. 377,612I dated February?, 1888. Y Application iled September 5, 1887. i Serial No.y 248,826. (No model.)

To all whom it may concern:

Beit known that I, HAMMOND V. Haras, residing at Cambridge, inthe ycounty of Middlesex and State of Massachusetts, have invented certain Improvements in'Telephone-Transmitters, of which 'the following is a specification. This invention relates to telephone-transmitters which are employed in connection with a battery, andwhichoperate to vary theresistance of, and consequently the current Howing in, the battery-circuit. It has more particular reference to that class of battery transmitters in which granular particles of conducting materlal, and specially of carbon, constitute the current-varying medium, they being confined in a loose and free state between two conducting-plates, which are thereby electrically connected, both of the said plates being included in the circuit of the battery. Heretofore such transmitters have 'uniformly been rigidly4 mounted either on a diaphragm oron a sepaL yrate support, and in the latter case one of the 'electrodes or plates thereof has been mounted upon or has itself constituted the vibrating diaphragm.'

My invention'consistsin providing two complete and independent current-varying organisms of the type described above, each being separately mounted on a springsupport and adjustable independently of each other, and both being in contactwith and adapted to operate in associationl with a single complement-` ary or opposing electrode, which latter is vibrated by and in accordance ywith the vibrations of the diaphragm and is adjustable with respect thereto, so that each full vibration of the said diaphragm is caused to effect a substantially equal but opposite change in both lcurrent-varyers, the resistance of one being increased at the same moment when the resistance of the other is decreased, and vice versa, said diaphragm and electrodes being combined with an induction-coil having a double and differentiallywound primary helix whose wires are in circuit one with eachof the spring-supportedelectrodes, and both with the diaphragm-electrode, all as hereinafter set forth.

The object of my invention is, generally, to produce a transmitting-telephone of improved efficiency, and to utilize to the fullest extent thevariations of resistance produced in its operation.

f 'In the drawings which accompany and illus- Y trate .this specification, Figure l is an elevation of the instrument` inclosed in a suitable case, with the cover and workingpartsp'artly in section and showing the circuits. Fig. 2is v a horizontal section of the same, but wit-hy the circuits and induction-coil superadded, in a section of the compound granulation-'holding buttons enlarged. v

' Ais'the transmitter-caso, formed upon th plan of the Well-known -Blake transmitter,

inggring'of rubber or similar materialfre'sts k6` 5 (the external form is, however, immateriaL)y ina ringfseat, C, afiixedto the cover, the necessary vocalizing-chamber being thus `formed between the diaphragm and a portion of the cover. The diaphragm is heldin placeby the Y clip e and dampingsspring s. From opposing points upon'the said ring-seat project brackets`16 and 2l', and tol these, by springlplates 18 and 24, are hung supportingblocks 19 and 23. The upper'block holds between pieces of insulating material a dat spring, 26, from which depends. the compound granulationholding button a. In like manner the lower block, 19, sustains, also, between pieces of insulating' material, the spring 20, vsupporting -the compound conductor-holding button a.

Both springs areinsulated from the diaphragm and surrounding elements by their. ynon-conducting clampingpieces, aswell as' by the pieces z' of non-conducting tubing which surroundthem. Bothsprings,withtheirdepend- Aentvbuttons, are adjustable with reference to one other and to any interposed conductor.k or Y electrode by thescrews 17 and 22, which, 'enterf-A ing the brackets 16 and 21, bear upon theblocks 19'and 23. A bracket, 39, isalsoafxed to the center of the inner surface of the vdia.- phragm, and has outwardly-projecting arms Y 4, which adjustably supporta cr0ssrod,"5, cai 10o Y 6or a conventional diagram. Fig. 3 is a view in pvable of sliding by sockets 7 upon them, and hich, when in its proper place, can be there iixed by screws 8.

About the middle ofthe rod 5 a small bluntpcnted metal stud, (platinum being preferred) projects both ways and makes contact with the inner conducting face or wall of both compound buttons, the surface of said faces being,ifdesired,plated or otherwise metallized for the purpose of improving the contact.

As shown in the drawings, each of the buttons a has a peculiar construction. Each is formed of a front plate, 12, and a back plate, 10, of carbon,insulated and separated from one u, another by an elastic intervening ring, 11, of

felt or rubber, to which both plates at their edges are aixed,thus forming an inclosed compressible and expansible chamber, within which is placed a quantity of granulated carbon or similar material. It will, however, readily be seen that while such a special button is to be preferred it is notan essential fearture, and an ordinary solid button may be employed, if desired. The induction-coil D is shown also in diagram in Fig/2 and has a double primary helix.

One pole of the local battery is connected with the binding-screw 13. This is united by wire t to the metal bracket attached to the diaphragm center and the circuit continues therefrom to the cross-bar and metal electrode 36. At this point the circuit bifurcates, oneV branch leading through the compound button a, which has its front plate in contact with the stud of the electrode 36,'and by wire g to one end of one of the primary helices,through the said helix and back to the other pole of the battery by wire j and binding-screw 14. The other branch leads from the electrode 86 through the button d', and then, vict the sus pending spring thereof and the wire h, to its own primary helix, and back to the opposite pole of the battery by the wire j and the same binding-screw 14. The two terminal ends fand k of the secondary helix connect, frespectively,with the binding-screws 15 and 16, and then to line, or to line and earth.

From the foregoing description it is obvious that the central electrode, 36, is in normal contact with both compound buttons, and this contact must remain permanent and unimpaired. Its pressure upon both is, however, capable of being greatly varied by the vibratory action of the diaphragm, and is, moreover, adjustable by the screws 17 and 22. When, by the condensation of the air-waves within the vocalizingchamber, the diaphragm makes an inward vibration, the electrode 36 increases its pressure against the button a, but the pressure of its contact with a is weakened. Furthermore, inasmuch as each of the said buttons is in itself a complete currentvaryer, and is, moreover, mounted on a yielding spring and vprovided with an elastic annulus between its two faces, the resist-ance under this action of both buttons is similarly but oppositely and simultaneously varied. We may assume, therefore,

that the resistance both of the button a as a whole and of the contact between the said button and the metal point 36 is lowered, and thus that the resistance of the branch g of the primary circuit is lowered to a degree representing the sum of these actions; and that the current fiowing in the primary circuit, forming the extension of such branch circuit, is in like manner increased to an extent inversely proportional to Vsuch depreciation or" resistance. And not only so 5 but the resistance of the button a as a whole and of its contact with the metal electrode 36 is increased by virtue of the lessened pressure between the said electrode and the inner face of said button, which permits the two faces thereof to increase their distance from one another and to weaken the contact of the inner one with the said electrode. The resistance in this branch of the circuit being thus at any given moment increased, the current is in the branch 7L of course decreased. Thus the electrical variationsin the secondary coil and main circuit 7c f have a much wider range than is usual, and when the air in the vocalizingchamber is again rareied the diaphragm expands outwardly and the foregoing actions are repeated reversely.

If simple buttons replace the compound buttons a and c', the change in resistance is at the points of contact with the electrode 36 only.

I do not broadly claim as my invention the use, in connection with a double-contact transmitter, of an induction-coil having a differential primary helix, that being claimed by S. WV. Robinson in Letters Patent No. 227,653, bearing date May 18, 1880.

Having now described my invention and its operation, I claim- 1. The combination,in a telephone-transmitter, of a Vibratory diaphragm, an electrode adjustably mounted thereon and adapted to be vibrated thereby, a pair of compound-button electrodes, each formed as hereinbefore described, and each independently supported upon an adjustable spring, by which the two buttons are maintained in permanent but vnf riable contact with the said diaphragm-electrode, one on each side thereof, and an induction-coil, having a secondary helix, adapted for inclusion in a main circuit, and a double and differentially wound or connected primary helix,each of the said wires being in circuit with one of the compound-buttons, and both with the diaphragm-electrode, substantially as described herein.

2. The combination, in a telephone-transmitter, of a vibratory diaphragm, an adj ustable electrode supported upon abracket mounted on the center of said diaphragm ,two springsupported compound-button electrodes, arranged to press with permanent but variable contact, one on each side of the said diaphragmelectrode, an adj listing-screw for each of the said buttons, whereby the initial contact-pressure thereof may be varied, and an inductioncoil having a double-wire primary helix, the

IOO

Y 377,612 I t 3 vtwo wires of vseid helix being in circuit each other, and vice versa, substantially as dewith one of the said 'compound buttons, and scribed. v v

both with asinglecontinuationleading through In testimony whereof I have signed my name l a battery and through the diaphragm-elec to this specication,in the presenceof two subv 5 trode, whereby the current of said battery is scribing witnesses, this 3d day of, September, r 5

caused to circulate in the two branches of the 1887. i

primary helix in opposite directions, and HAMMOND V. HAYES.

' whereby thesaid current may, by the vibrar i Witnesses:

tions of the diaphragm, be simultaneously in- GEO. WILLIS PIERCE,

ro creased in one branch and diminished in the ""FRANK C. LocKwooD. 

